Inconceivable._________________"Method goes far to prevent trouble in business: for it makes the task easy, hinders confusion, saves abundance of time, and instructs those that have business depending, both what to do and what to hope."
William Penn 1644-1718

Many service organizations will have templates. Many consultancy organizations and people will have templates. There may even be some findable on the web. Some will be labelled "generic" and those will either be too vague, to big (to cover everything possible), or to ungeneric.

If you start from the perspective of looking for a "standard" because you are not sure what to do you will be very lucky indeed (remember the probability machine?) to end up with something that meets what you need.

The "customer friendly" bit is just the final nail in the coffin. Everything about a capacity plan has to be focussed on your infrastructure and your services and whatever you mean by "customer friendly" has to be focussed on your customers.

If you want very generic, and I'm not even sure about this:

0. Determine the time and calendar considerations for peak demand/usage.
1. Measure utilization.
2. Measure capacity.
3. Express the difference and make it your baseline.
4. Anticipate growth - business knowledge required.
5. Anticipate change - business knowledge required.
6. Anticipate new systems - business knowledge required.
7. Anticipate new and replacement software and hardware in your infrastructure.
7a. Watch out for technology change smashing your assumptions (e.g. when fast disk cache became so large that latency and seek went out the window).
8. Project future requirements from all this.
9. Determine risk tolerance.
10. Project timescales for extending (or contracting) capacity.
11. Propose appropriate actions._________________"Method goes far to prevent trouble in business: for it makes the task easy, hinders confusion, saves abundance of time, and instructs those that have business depending, both what to do and what to hope."
William Penn 1644-1718